Before yesterday, Zynga’s stock had gained 44 percent since its December initial public offering. Above is CEO Mark Pincus.

February 16, 2012

Zynga Inc., the biggest developer of games on Facebook, fell the most ever after a report showed product-development costs weighed on quarterly profit. Earnings fell 34 percent to $67.8 million from a year earlier, the San Francisco company said. Research and development costs jumped more than eightfold to $444.7 million last quarter. Sales and marketing expenses almost tripled, to $112.2 million.